Integrated process for the separation of air and an integrated installation for the separation of air

ABSTRACT

Air is compressed in an air compressor to produce a stream of compressed air, wherein at least part of the stream of compressed air is sent from the compressor to an air separation unit. The air separation unit produces a fluid enriched in a component of air, wherein the fluid is sent to a first unit in which an exothermic process takes place. The heat generated by the exothermic process is used to produce steam. At least part of this steam is sent to a steam turbine, where the work generated by the steam turbine is used to power at least the air compressor, and a product of the air separation unit is sent to a further unit in which at least one additional process takes place.

BACKGROUND

The present invention related to an integrated process for the separation of air and an integrated installation for the separation of air.

Air separation units are frequently used on industrial sites where several types of processes requiring products of the air separation unit are located. When one of these processes is exothermic and when cheap sources of heat are simultaneously available, the heat produced is sometimes released to the atmosphere or at best not recycled to its fullest potential: it becomes more economical to waste these cheap sources rather than to expend some capital in energy recovery systems.

It is an object of the present invention to use the air separation unit to transfer the energy produced by the exothermic process to another process in the form of a product of the air separation unit.

The air separation unit may be of any known kind but will preferably be a cryogenic distillation plant.

SUMMARY

According to one object of the invention, there is provided an integrated process for the separation of air in which:

-   a) air is compressed in an air compressor to produce a stream of     compressed air; -   b) at least part of the stream of compressed air is sent from the     compressor to an air separation unit producing a fluid enriched in a     component of air; -   c) the fluid enriched in the component of air from the air     separation unit is sent to a first unit in which an exothermic     process takes place; -   d) heat generated by an exothermic process taking place within the     unit is used to produce steam; -   e) at least part of the steam is sent to a steam turbine -   f) work generated by the steam turbine is used to power at least the     air compressor; and -   g) a product of the air separation unit is sent to a further unit in     which at least one further process takes place.

According to a further aspect of the invention, there is provided an integrated apparatus for the separation of air comprising:

-   a) an air compressor and a conduit for sending air thereto to     produce a stream of compressed air; -   b) a conduit for sending at least part of the stream of compressed     air from the compressor to a first air separation unit producing a     fluid enriched in a component of air; -   c) a first unit in which an exothermic process takes place and a     conduit for sending the fluid enriched in the component of air from     the air separation unit to the first unit; -   d) a boiler for producing steam using heat generated by an     exothermic process taking place within the first unit; -   e) a conduit for sending at least part of the steam to a steam     turbine; -   f) means for transferring work generated by the steam turbine is     used to at least the air compressor; and -   g) a conduit for sending a product of the air separation unit to a     further unit in which at least one further process takes place.

BRIEF DESCRIPTION OF DRAWINGS

For a further understanding of the nature and objects for the present invention, reference should be made to the following detailed description, taken in conjunction with the accompanying drawings, in which like elements are given the same or analogous reference numbers and wherein:

FIG. 1 is an illustration of one embodiment of the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

An integrated process for the separation of air is provided in which:

-   a) air is compressed in an air compressor to produce a stream of     compressed air; -   b) at least part of the stream of compressed air is sent from the     compressor to an air separation unit producing a fluid enriched in a     component of air; -   c) the fluid enriched in the component of air from the air     separation unit is sent to a first unit in which an exothermic     process takes place -   d) heat generated by an exothermic process taking place within the     unit is used to produce steam; -   e) at least part of the steam is sent to a steam turbine; -   f) work generated by the steam turbine is used to power at least the     air compressor; and -   g) a product of the air separation unit is sent to a further unit in     which at least one further process takes place.

Additional embodiments of the invention may include one or more of the following features:

-   -   the product of the air separation unit sent to the further         process is a fluid enriched in oxygen;     -   the product of the air separation unit is a fluid enriched in a         component chosen from the group comprising oxygen, nitrogen and         argon and a fluid enriched in the same component is sent by a         further air separation unit to the further process;     -   the further process is an exothermic process, heat generated by         the further process is used to produce steam, at least part of         the steam is sent to a further steam turbine and work generated         by the steam turbine is used to power a compressor of the         further air separation unit     -   the exothermic process is a gas-to-liquids conversion process;     -   the further process is chosen from the group comprising a DME         conversion unit and a methanol conversion unit;     -   all the steam produced by the exothermic process is used in the         steam turbine;     -   the exothermic process taking place within the unit consumes the         fluid enriched in the component of air from the air separation         unit and produces steam; and     -   one exothermic process taking place within the unit consumes the         fluid enriched in the component of air from the air separation         unit and a further exothermic process taking place within the         unit produces steam.

An additional aspect of the invention, provides an integrated apparatus for the separation of air comprising:

-   a) an air compressor and a conduit for sending air thereto to     produce a stream of compressed air; -   b) a conduit for sending at least part of the stream of compressed     air from the compressor to a first air separation unit producing a     fluid enriched in a component of air; -   c) a first unit in which an exothermic process takes place and a     conduit for sending the fluid enriched in the component of air from     the air separation unit to the first unit; -   d) a boiler for producing steam using heat generated by an     exothermic process taking place within the first unit; -   e) a conduit for sending at least part of the steam to a steam     turbine; -   f) means for transferring work generated by the steam turbine is     used to at least the air compressor; and -   g) a conduit for sending a product of the air separation unit to a     further unit in which at least one further process takes place.

Additional embodiments of the invention may include one or more of the following features:

-   -   the product of the first air separation unit is a fluid enriched         in a component chosen from the group comprising oxygen, nitrogen         and argon and comprising a conduit for sending a fluid enriched         in the same component from a further air separation unit to the         further process;     -   the further process is an exothermic process, and comprising a         further boiler for producing steam using heat generated by the         further process, a further steam turbine, a conduit for sending         at least part of the steam from the further boiler to the         further steam turbine and means for transferring work generated         by the further steam turbine is used to power a compressor of         the further air separation unit.

A preferred embodiment of the invention will be described with reference to FIG. 1, which is a block diagram of the integrated installation.

An air separation unit 1, which may be a cryogenic distillation unit, separates air to form at least an oxygen enriched product 3, which may be in liquid or gaseous form. At least part of this product is sent to a unit 4 in which an exothermic process takes place, such as a Fischer-Tropsch synthesis gas conversion process. Heat produced, by the synthesis gas conversion process or another associated process within the unit 4, is used to raise steam 5 in a boiler 7, the steam 5 is sent at least to the air separation unit 1 and the steam powers a steam turbine 6 coupled to a compression system 8 of the air separation unit, for example the air compressor for the air separation unit feed air (not shown). Where the compression system is the air compressor, the air is then purified and cooled and sent to the distillation columns in known manner so as to produce products enriched in a component of air.

A further fluid 2 which may be oxygen enriched, nitrogen enriched or argon enriched and in gaseous or liquid form is sent from the air separation unit 1 to the further unit 14 in which at least one further process takes place. The further process fed by the further fluid may be exothermic or endothermic.

The installation may also include a further air separation unit 11 in which air is separated to form a fluid enriched in at least one component of air. A product 13 of the air separation unit which may be enriched in oxygen, nitrogen or argon may be sent from the further air separation unit 11 for the further process unit 14. The further process unit 14 may produce heat which is used to raise steam 15 in a boiler 17. In this case, the steam 15 may be used in at least one steam turbine 16 to power at least one compressor 8,18 of the first or further air separation units 1,11. Where the compression system is the air compressor, the air is then purified and cooled and sent to the distillation columns in known manner so as to produce products enriched in a component of air.

Within the further process unit 14, one and the same process may be fed by the product 2 or products 2, 13 and produce the steam 15. Alternatively one process within the unit may be fed by the product 2 (or products 2,13) while another associated process produces the steam 15. For example a natural gas reformer may be fed by oxygen 2 and a Fischer Tropsch converter may produce steam.

It will be appreciated that while only one embodiment of the invention has been shown and described hereinabove, many modifications may be made by the person skilled in the art without departing from the spirit and scope of this invention. 

1. An integrated process for the separation of air in which: a) air is compressed in an air compressor to produce a stream of compressed air; b) at least part of the stream of compressed air is sent from the compressor to an air separation unit producing a fluid enriched in a component of air; c) the fluid enriched in the component of air from the air separation unit is sent to a first unit in which an exothermic process takes place; d) heat generated by an exothermic process taking place within the unit is used to produce steam; e) at least part of the steam is sent to a steam turbine f) work generated by the steam turbine is used to power at least the air compressor; and g) a product of the air separation unit is sent to a further unit in which at least one further process takes place.
 2. The process of claim 1, wherein the product of the air separation unit sent to the further process is a fluid enriched in oxygen.
 3. The process of claim 1, wherein the product of the air separation unit is a fluid enriched in a component selected from the group consisting of oxygen, nitrogen and argon and a fluid enriched in the same component is sent by a further air separation unit to the further process.
 4. The process of claim 3, wherein the further process is an exothermic process, heat generated by the further process is used to produce steam, at least part of the steam is sent to a further steam turbine and work generated by the steam turbine is used to power a compressor of the further air separation unit.
 5. The process of claim 1, wherein the exothermic process is a gas-to-liquids conversion process.
 6. The process of claim 1, wherein the further process is selected from the group consisting of a DME conversion unit and a methanol conversion unit.
 7. The process of claim 1, wherein all the steam produced by the exothermic process is used in the steam turbine.
 8. The process of claim 1, in which the exothermic process taking place within the unit consumes the fluid enriched in the component of air from the air separation unit and produces steam.
 9. The process of claim 1, in which one exothermic process taking place within the unit consumes the fluid enriched in the component of air from the air separation unit and a further exothermic process taking place within the unit produces steam.
 10. An integrated apparatus for the separation of air comprising: a) an air compressor and a conduit for sending air thereto to produce a stream of compressed air; b) a conduit for sending at least part of the stream of compressed air from the compressor to a first air separation unit producing a fluid enriched in a component of air; c) a first unit in which an exothermic process takes place and a conduit for sending the fluid enriched in the component of air from the air separation unit to the first unit; d) a boiler for producing steam using heat generated by an exothermic process taking place within the first unit; e) a conduit for sending at least part of the steam to a steam turbine f) means for transferring work generated by the steam turbine is used to at least the air compressor; and g) a conduit for sending a product of the air separation unit to a further unit in which at least one further process takes place.
 11. The apparatus of claim 10, wherein the product of the first air separation unit is a fluid enriched in a component chosen from the group comprising oxygen, nitrogen and argon and comprising a conduit for sending a fluid enriched in the same component from a further air separation unit to the further process.
 12. The apparatus of claim 11, wherein the further process is an exothermic process, and comprising a further boiler for producing steam using heat generated by the further process, a further steam turbine, a conduit for sending at least part of the steam from the further boiler to the further steam turbine and means for transferring work generated by the further steam turbine is used to power a compressor of the further air separation unit. 